


Mage Casting

by sleeepyinseattle



Category: Undertale (Video Game)
Genre: Angst with a Happy Ending, Gen, Good W. D. Gaster, Healing, Human, Hurt/Comfort, Magic, Parent Grillby (Undertale), Scientist W. D. Gaster, Veteran Grillby, War, humans are shit creatures, i don't know how tags work lol, i forgot when i started it, i guess, idk - Freeform, it was before the latest chapter i think, its shit but i love it, kinda angst, long chapters, loosely based off of casting rain by silverskye13, mostly just writing practice, post chapter 70-ish?, sorta?
Language: English
Status: Completed
Published: 2018-03-28
Updated: 2018-04-02
Packaged: 2019-04-13 23:22:39
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 4
Words: 13,835
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/14123061
Author URL: https://archiveofourown.org/users/sleeepyinseattle/pseuds/sleeepyinseattle
Summary: (A sort-of related AU based on “Casting Rain” by silverskye13)On a rather routine attack against a human encampment, Gaster and Grillby stumble on a terrified human. Who- despite their intimidating appearance and the fact that, you know, these monsters aresupposedto be killing humans- doesn't seem all that worried. And boy, do they have a secret.





	1. A Human Approaches!

**Author's Note:**

  * For [Silverskye13](https://archiveofourown.org/users/Silverskye13/gifts).



> So I worked on this mostly in one night, on a whim. Characters are inspired by silverskye13's "Casting Rain" crew. But, you know, it's an AU so they're going to act a bit differently. I wrote this all in sections, without chapters. So there's going to be some interesting shenanigans going on as far as that. Just a heads up. 
> 
> Baby's first fic of a fic? Is that even a thing?

Grillby motioned his force forwards, reminding them with a tense spark to _be quiet_. Thetis’s reports indicate a mage in the area, and he _really_ didn’t want to have one swoop down in a surprise. This time, he didn’t want to burn down a whole forest. From ten feet away, Gaster shifted, listening to the sounds around them. The distance between them obscured the skeleton’s expression; it hurt a bit, not having Gaster at his side. Dispelling those thoughts, he pressed onwards, towards their destination.

Beyond the forest sat a human encampment, well dug in and fortified with wooden spikes. As far as those were concerned, Grillby had it covered. The flare of confidence inside him flickered in apprehension. Gaster looked over at the elemental with wary eyes. Even at this distance, Grillby could tell.

Fifty feet forward, the bushes rustled loudly. It couldn’t have been any monster under his command. He saw a look of dawning terror on Gaster’s face as they looked in that direction. Protective and worried, Grillby stepped closer to the doctor. Purple magic hummed from Gaster’s hands as Grillby fanned himself brighter, hand on the hilt of his sword. They shared a quick look of, ‘well fuck.’ He put up a fist to signal for his forces to halt. To focus. To ready for attack.

Another, closer, louder rustle. Then another, closer still. Whoever it was, they were almost in sight.

Moving just slow enough for it to be silent, Grillby drew his sword. It glinted in the dappled moonlight and reflected back the glow of his core.

Then they heard the rustle again, closer. Now they could hear footsteps, hard foot falls of someone running towards them. From his peripheral vision, Gaster’s floating hands appeared, tense with determination. If the humans were bringing the fight to them, a fight they will have.

Then they saw it. A single human, dashing out from the brush, stumbling on the ground. They clutched a dark cloak about their shoulders, red hair dyed crimson at the ends. The smell was unmistakable—blood. And magic. Strong magic, that made his nose itch and quiver. With a swift motion, Grillby drew the point of his blade higher, right at the human.

They stumbled over a root and fell forwards, wincing. But they did not cry out. Turning for a quick glance over their shoulder, the human pushed themselves to a stand.

Then they looked up.

Terror whipped through their eyes and they stumbled back, tripping over the loose root again and falling against a pine. A sharp gasp of pain escaped them. But they did not cry out. Tears welled up in their eyes as they drew the cloak tighter about their shoulders, looking the monsters up and down.

Sword still raised, Grillby marched forwards. His fire crackled with intent; any empathy he harbored for the humans had long since been trampled. Thistle and her bastardization of monster magic, the mage with that blinding white power—images of them whipped about in his mind as his eyes gleamed. Steely and cold, he held the sword against the human’s chest, drawing a small bead of blood. They closed their eyes, whispered a quick sentence he could not understand, and waited.

He paused.

This human kid was more terrified child than bloodthirsty mage. His emotions burned inside his stomach—he was obligated to kill them. It was his duty, the reason why he was summoned. But the presence of Gaster behind him gave him room for thought. He didn’t spare Rowan. But he did spare the children before. They too were terrified, fleeing for their lives. And harmless. This human seemed harmless. He _could_ spare them, and not be guilty. He _could._

Gaster looked to Grillby, waiting for the inevitable. Were it him there, he’d have scooped them up in his arms and taken them away. They were just a kid. Unbridled, thoughts of Rowan, of Cris and Cole and Ava, sprang into his mind. He guessed he had a soft spot for children. He signed in decisive, angry movements, “What are you waiting for, firefly?”

He really hoped Grillby wouldn’t do it.

The elemental himself almost didn’t want to. But he _had_ to. He had his company to think of, the brave soldiers risking their lives under his command. Now wasn’t the time to show weakness, when they needed a solid foundation. Someone to look towards for strength. Taking a breath, Grillby pushed the blade of the sword in a bit further. Through the tip of his sword, he felt bone underneath the skin and muscle. He felt the quivering of the human’s breath. He felt the rapid pulse of their heartbeat. But they did not cry out.

Instead, they closed their eyes and said, “I mean you no harm.” The words tumbled from their lips, no more than a whisper on the wind.

The elemental had expected them to curse him with a dying breath. Gaster took a half-step back, looking the human over again. He did his best not to scowl at Grillby as he looked at the elemental. Waiting.

“I only wanted to get away…” The human breathed, their eyes shifting down to the blade in their chest. Then, their eyes flickered back where they came. Towards the human encampment Grillby’s forces intended to wipe off the map. “I’ll go in peace if you’ll let me.”

Though he couldn’t understand why the human wasn’t fighting for their life right then, Grillby could hear sincerity in their voice. Looking to Gaster, he took their words in. “ _You_ don’t trust them, do you?” Gaster’s signs carried a hint of contempt. “’Cause they’re a human.”

“They may have information,” he mumbled. Of course, he didn’t know if that were the case. All he did know is that he didn’t want Gaster to be angry with him for much longer. It drained him to think that his one friend left on this earth hated his entire soul. Maybe, this could make it better. Maybe, this could show Gaster that he was relearning what it felt like to have empathy. Maybe, this would make him feel better about himself.

Withdrawing his sword from their chest, he sheathed it. Then, tentative and slow, he took a couple steps towards the human. Crouching, he held out a hand. The human looked back at him, all confusion and fear. Shaking their head, they pushed themselves to a stand, wincing as their back slid over the tree. They took a step to the side, away from Grillby.

A hand shot out, gripping their shoulder. Another wince of pain shot over their face as they looked up at him, tearing up.

“I can’t let you go,” Grillby grumbled, smoke pouring from his mouth. The look of terror shot through the human’s expression again. They began shaking again, as though buffeted about by the winds whistling through the trees. From behind him, he heard murmurs of assent from his soldiers. From behind him, he heard the bloodlust in their voices. From behind him, a creeping sense of dread crawled up his back.

The memory of that tiny mage, their neutral tone, that damning question. He was an elemental. He was a commander. He was a monster—it was written in his soul to protect his unit from humans. The niggling sense of self doubt crept back in when he saw the human tearing up again. Their legs seemed unable to hold them up and yet, they did. Dogged, their body told them to keep going despite knowing, full well, that they were not going to see the morning.

“But I won’t let you die,” he breathed. This, at least, he could do.

From behind him, the whispers stopped. Gaster pushed forwards, a hand on Grillby’s arm. “Sparks, you’re not serious?” There was a small light of hope in the skeleton’s eyes, the white blips glowing a bit brighter than before.

“That’s what I said.”

“They’re a _human_ , Grillby—” he breathed. But Grillby turned to his friend, eyes narrowed.

“And they’re just a kid,” he said.

With a breath of trepidation, Gaster took his hand off the elemental’s arm. Relief crept over the human’s face, almost chasing away the terror and confusion. It lingered as they looked between the two monsters before them.

Another murmuring breeze picked up behind him. He ignored their dissent and held out his hands to the human, offering them his help. They shook their head, mumbling something.

“They need to leave,” Gaster reminded him. Grillby frowned. He was doing this for Gaster, how could the skeleton not see? “Honestly, firefly.” He looked at his friend. “What can we do?”

“I…” he sighed, watching the human stare at the two of them. He could take the human back to the fortress, back to King Asgore. The king of all monsters could decide for him. He wasn’t the one killing the poor kid, so Gaster had nothing to hate him over. “I don’t know.” Holding out his hands again, he added, “But I know I need to try.”

“They haven’t bewitched you,” Grillby signed, hands pointing at the human in jest. A wan smile crossed his mouth. When Grillby shook his head, the doctor smirked a bit wider. Shrugging, he looked back towards the soldiers standing, waiting in awkward silence. “You’ll have to tell them.”

“I know.” As he put a hand on the human’s back, two things happened at once. He felt a stinging sensation in his hand—the same as if he’d touched a wet stone. And the human buckled forwards, breath drawn through gritted teeth. Snatching his hand back, he looked at his palm quizzically. Any liquid there had burned off, leaving it just as clean as before. Shrugging inwardly, he turned to his soldiers. “We will continue. The plan is unchanged. Gaster—” he looked back at his friend—if he could call the skeleton that anymore, “stay back within the forest. Fight from there unless we are in dire need of help.” Eyes glancing over the human, he added, “Keep them in your sight.”

Some part of him expected dissidence. He himself had felt some form of conflict—the others must, too. He beat it down as he beat the flames of his fire brighter. “We fight at dawn.”

The monsters—his monsters, those he’d trained and seen through battles against terrible humans—nodded in assent. Their commander had made a decision. A decision they were expected to respect. Even if they didn’t quite understand why. A few did so with a reluctance that spoke of the same battle within his own mind. He had no right expecting them to find some scrap of empathy the war hadn’t eradicated yet. He had no right to ask them to forgo decades of war and centuries of oppression over one human. He had no right to change their minds. Especially not if he could barely make up his own.

But he could command them to do this.

The human, through all of that, still looked as though death stood in their doorway. It probably did appear that way—a terrifying elemental brandishing a sword and a cracked, black-robed skeleton staring them down.

But they did not cry out.

“I can trust you to look after one human,” Grillby said, “But tell them to keep quiet.” He did. And they did.

Quiet, tense hours passed as Grillby’s forces pushed their silent way through the forest, now with the human in tow. They did not say much, save for a whispered “Thank you,” directed towards Grillby. For his own part in this development, Gaster seemed confused. “Why,” he signed, fingers flickering in frustrated quickness, “did you _ever_ decide to do that?”

Grillby shrugged. It would probably be best to keep his thoughts secret. It burned in his soul to keep it from Gaster, but he did. If he told the skeleton that the single reason he spared this human was to prove that he _could_ , the last of their friendship would fizzle up and burn. That was the last thing he wanted. Instead, he just shook his head at any questions from Gaster.

Trudging alongside them, the human stayed quiet. Both the monsters could see a shimmer of sweat lining their forehead, a glitter that matched the dampness on their back. It hadn’t rained or snowed despite the spring weather. Bitter winds that whipped through everything, perhaps, but nothing from the sky. As they reached the edge of the forest, they stopped. Grillby sent word around that no fires were to be lit. He dimmed himself, pulling his hood over his flames.

When the human saw where they were, worry flashed over their face. As the forces sat down to wait out the hour or so before their strike, they quivered, drawing themselves into a small ball. The cloak pooled around where they sat, making them seem even smaller than before. Small, and frail, and helpless. Like Rowan. Grillby stood on one side of them, turned so he could observe his troops. Gaster took the human’s other side, flanking them. Caging them in, just in case they tried something.

As he was wont to do, in the silent time they waited, Gaster examined the human. The lights in his eyes examined their head, noting the darkness of their hair. He saw scratches on their knuckles and palms, rope burns on their wrists. Their toes ice beneath the cloak; they didn’t have any shoes on. As his eyes traced over their every feature, the human’s eyes stayed transfixed. Only blinking took their gaze off the encampment. Minutes passed and the did not move; the terrified stare sent a shiver up Grillby’s core. Signing to Gaster, he goaded him on. Get the skeleton to feel sorry for the human. Get him to like the human. Get him to see that Grillby _could_ be empathetic. “You’re a doctor. Ask them if they’re injured.”

Tentatively, Gaster reached out to put a reassuring hand on the human’s shoulder. He spoke in hushed tones, mumbling that Grillby won’t let anyone hurt them further. Shaking themselves a bit, they tore their eyes away from the encampment to stare at Gaster. With a nod, they looked back. The doctor pressed forwards, “Are you injured?”

Shaking their head, the human said, “I’m fine.” They curled inwards, shrugging off his hand.

Only then did he see the blood on his palm. He looked at the glistening on their back and—if he could—blanched.

The patch of gleaming blood on their back stretched from their shoulders down to their hips, and from one arm to the next. It stuck to their spine and shoulder blades, shifting as they took shallow breaths.

Guilt wracked through the skeleton as he signed back at Grillby, carefully drawing out the extent of the damage without touching the human. His friend flickered back at him. “Will they be alright?” See? Empathy. He’d leave the murdering of a human child to King Asgore. Keep his fiery hands clean.

Looking at the human, who seemed as pale as the moonlight and a touch green, Gaster shook his head. “Not unless I can heal them now.”

Grillby looked back at the human, and at the horizon. Dawn edged closer, the sky tinging the slightest bit of blue as it heralded the sun. “Keep them alive,” he breathed, turning to his men. He signaled for them to rally, to stand and ready themselves, to prepare.

The human startled at the movement, turning around with terror anew in their eyes. Gaster put a hand on their head. Jumping a bit, they turned to look at him as he explained in a low voice. With another quiet nod, they looked back at the battlements.

In a minute, Grillby and his army drove towards the encampment, and the two were alone. Gaster stood, walking to the edge of the forest to watch. In a matter of minutes, the plan was a success. It was… terrifying to watch. With a fervor that would put Mistral of the Storm to shame, Grillby lit up the wooden stakes. The humans inside scrambled, tents ablaze as they tried to pull together some semblance of defense. Looking back, Gaster was surprised to see the human still sitting there, watching. No sorrow illuminated their expression. Just a cold sense of defeat. Their head slipped from their arms. If he pulled their cloak around just so, he could almost forget they were there and not a stone. With a quick check of their HP, he looked back.

It was easy, from his vantage point and relative cover, to pick off any soldiers running from the encampment.

That was easy. What wasn’t was the light of magic and the wave of terror it brought. A mage. There was a mage there. The one from Thetis’s report. But he didn’t expect the mage to be _here_. He watched the flames of Grillby’s magic light up the early morning. Flares, towers of molten fire, lances exploded against the mage’s defense. A minute or two slipped by. He picked off two more fleeing humans. And as suddenly as they’d found them, he felt a ripple of dispelled magic as the mage died.

Grillby the Mage Slayer, indeed.

A couple minutes later, Gaster could see a single soldier jogging towards him. Grillby was going to burn the whole thing down, and then they were off. Back the three-day’s trek to King Asgore’s fort. With a nod to the monster, the skeleton looked back.

Any momentary joy seemed to slip from him. From where they sat, the human had slumped over to the ground. Even from where he stood, he could hear their ragged breathing. It was the loudest noise they’d made yet. Sweat soaked their face, and as he turned them over, he could see the battered remains of a shirt clinging to their shoulders and torso. It, too, was glistening with sweat and spattered with blood. He checked their HP, and with a quiet curse, pulled their soul out of their chest.

The heart in his hands glowed green. The green of new shoots, of early spring. It was beautiful. But he didn’t have time to enjoy its glow. As the monster messenger stood at the edge of the trees, a worried look his way, he pulled the soul apart, weaving it back together. With one eye, he watched their HP before it drained any further. With the other eye, he unspun the threads of their soul and asked—no, _commanded—_ them to stop bleeding.

It worked. With a tense sigh, the human relaxed in their unconsciousness. He put a hand on their shoulder and shook them. He tried it again. He put a hand on their face and told them to come back. The human stayed still, resolutely unconscious. But alive.

When he looked up, the messenger was gone. Behind him, the encampment was flickering out, the fire that consumed it swallowed up by Grillby. The elemental himself was striding back to the forest’s edge, concern whipping through in shades of yellow and green.

The elemental nodded. “No humans got past you?” Grillby asked, looking at the scattered bodies trailing from the remains of crumbling wood and debris.

Gaster shook his head. “Target practice,” he smirked. Looking down at the human, he sighed.

 “What happened?”

“They almost bled out, that’s what.” He sighed, standing up. “I stopped it, but they’re barely hanging in there.”

 “We will rest here a few hours,” Grillby said to his troops. A small cheer of pleasure rang out in the early morning air. “Then the march back.” Someone groaned, eliciting laughs and jests that bubbled up from others.

The monsters gathered some wood from the forest and settled to a quick breakfast, talking good-naturedly amongst themselves. The commander had done his job well—the monsters who received wounds in the battle were minor. No one had died. Well, on their side, at least. Grillby crouched next to the human, gingerly picking up a corner of their cloak and wrapping it around them. Slowly, in imperceptible increments, the human curled closer to him. The skeleton let out a bark of laughter as Grillby flickered pink and yellow. “Embarrassment looks good on you, firefly.” Much better than the deep reds, those angry lights that seemed to consume any pleasantness around him.

“Quiet.”

“Now will you tell me why you decided to _save a human_?”

With a sigh, Grillby tried to explain it as best he can. Did he mention the child mage? No, he beat around that particular bush, instead passing it off as a worry he’d come to on his own. Did he mention he still felt nothing for the little human? That this was all a way to get Gaster to like him again? No, he didn’t mention those things either. He said little, and left most of it up to interpretation.

“They’re not… going to hurt anyone. So, I decided that, well, maybe I could let them live.”

“Grillby,” the skeleton said, sighing a bit, “It’s your job to kill _mages_. You killed one just now.”

“I did. But…” He trailed off. “When we came to rescue you. When that barrier broke down, and I fought Thistle over and over.” With a shaking breath, he confessed, “I killed that little kid mage.”

For a minute, Gaster sat still. His hands didn’t move about, quietly talking to himself. He barely blinked—instead, he froze. Worried, Grillby reached a hand out and put it on his friend’s arm.

“I know,” the skeleton said, “you told me.” He looked up at his friend, trying to mask the disappointment. “And you’ve felt guilty all this time, firefly?” His face seemed much more open. With a pain in grillby’s core, he could feel the skeleton starting to forgive him. Starting to believe his lie. Everything would be right as… well, not rain… but something inside of Grillby twisted and writhed.

“…Yes.” The elemental really hoped Gaster couldn’t hear the insincerity in his voice as he answered. He tried not to burn guilty blues and oranges. The hues shifted to yellows and purples.

Gaster just laughed. The skeleton just thought he was embarrassed. It relieved him of quite a lot of worry that sat between his shoulders. It felt like one of Thistle’s spears had lodged itself there. But it melted then. He smiled a bit brighter than usual. “Well, firefly,” Gaster chuckled, “I’m glad you told me.” The two of them looked back at the human now almost cuddled around Grillby’s feet. “But really, you think they could have information?”

“We’ll know once they wake up.”

“And what happens after that?”

“I don’t know.” It was becoming all too frequent, that phrase. But he did have a plan. He just didn’t want to tell Gaster. He wasn’t used to keeping so many, writhing lies inside. It didn’t feel great.


	2. Not Exactly What They Expected

**Summary for the Chapter:**

> In which I reveal that Gaster is something of a sap, and Grillby learns that sometimes it's okay to lie (so long as you start believing in the lie, too).

Once Grillby instructed his soldiers to ready to leave, they realized that the human couldn’t wake up. Panicked, Gaster checked their stats again. In all that time, their HP ticked up a single point. Sighing, Grillby took the human in his arms. Gaster smirked at him and arranged their cloak so it wouldn’t singe the elemental as they walked. The elemental turned away, not looking towards his friend. For the second time that day, Gaster passed it off as hiding a blush.

The day passed before the human awoke. Their head lolled to the side and, with a quiet groan, they opened their eyes. From where they lay, their cloak draped over them, they could see Grillby tending to a fire. The human blinked, looking around. They took in the tent, Gaster busying himself with herbs and boiling water, monsters in the distance readying for dinner and a night’s rest. Weak, they pushed themselves onto an elbow, trying to sit up.

“Easy there, kid,” Gaster said, putting a gentle hand on their shoulder. After all that rest, their HP was still low. Lower than he expected. They weren’t healing like they should. “You shouldn’t be moving too much.” In response they nodded, but pushed themselves up to sit.

With a sigh, their cloak fell off their shoulders. In the light of the crackling fire, Gaster could see the full extent of their wounds. Whatever shirt they’d had on was torn and slashed away from their whole back. The doctor recognized human, magical runes carved into their back. The lacerations formed a sort of diamond, from one shoulder to the other, starting at the nape of their neck and down past their trousers. Some cuts sunk deep enough that, when the human took in a breath, he was convinced their ribs showed through. All the cuts were raw—without Gaster’s earlier soul-tinkering, they would probably still be bleeding.

“What in the gods’ names…” he whispered. That could be why the human wasn’t recuperating fast enough. Like Rowan, the spell scored into their flesh kept draining any energy their soul had. There wasn’t enough for it to heal their wounds, too. Just enough to keep them alive, at the most.

Startled, the human looked at him. They looked confusedly at him, then towards their back, trying to see more than a haze of flesh and blood. “Did you… know this was there?”

“…Know what was there,” the human mumbled.

“Runes,” he answered, using a tip of his finger bones to draw the shape of one in the dirt. “All over.” He winced as he saw the human’s HP drop down a point. Three health. It was too, too low.

“Runes?” Their breath hitched, chest heaving. “What runes!?” Grillby looked up. When he saw the human turning around in a panic, he flickered a color of concern to Gaster. The doctor pointed at the human’s back and Grillby stared. If Gaster looked that concerned, that worried, then…? Leaving the pot of stew cooking on the fire, he dashed over, filly ready to play the part of concerned individual.

Gaster picked up his mixture and sat down beside the human. “Someone…” he said, running a skeletal hand over his temples, “carved runes into your back.” When their face showed no trace of understanding, he tried to explain what he saw. He showed the human what he had, told them it’d help. Pointed to where Grillby could find some clean fabric for bandages. Asked them if they would let him help.

A little reluctant, they gave him a careful nod. “They… they did that?” The human’s breathing stuttered as Gaster applied the herbs to the gashes. Grillby hovered, not understanding, but radiating worry. He stood lamely to the side, holding Gaster’s bandages and medicine as he let the doctor work.

“Who is ‘they?’”

And the human explained. That they used to live to the north, in a small town. A place small enough to grow excited by any new visitor. About the festivals they held in the summer, and the visitors that would come. Monster and human alike seemed to enjoy the bonfires, the stories, the atmosphere. They spoke of the migrant workers who’d come for the harvest and leave their stories of adventure behind. Of the mages who asked for healers and soldiers, anyone who could help win the war.

“You went with them?” Gaster asked, flicking a worried look at Grillby. The elemental flickered in false yellows and greens.

“No.” They shook their head. “I was apprenticed under a hedge witch to learn to heal.” As they saw that Gaster did not understand, they clarified, “A hedge witch heals the injured, cures the sick, helps deliver babies, those kinds of things. They deal with herbs and potions.”

“So, you’d understand when I told you that this has yarrow and comfrey?” He showed the human a glob of the medicine on his fingers.

“Yarrow stops the bleeding and comfrey closes the wound.”

Happily surprised, Gaster nodded for them to continue.

“They wouldn’t take our hedge witch—she’s too old to travel. They took me instead.”

A bit hesitant, picking and choosing his words with effort, Gaster asked, “How did you not know about this?” The human shivered as he put another dollop of the medicine on a deep cut.

“I… don’t understand how. There…” Their fingers gripped the cloak they wore, clutching it close to their chest. After taking a steadying breath, they said, “There were days when everything was white. And then it hurt—I think I fell asleep after that. I… don’t know how long that was.” They shook their head, a couple stray hairs sticking to the herbs of Gaster’s mixture. “It felt like… forever.”

While the human spoke, Grillby’s hovering grew more awkward. He could understand nothing about what was going on, but he could see Gaster soften. Where before he kept the human alive because Grillby wanted him to, now the skeleton seemed to care. Something about that made his core feel a bit warmer.

After their story, and Gaster had finished covering the goop up with bandages, he instructed the human to lay on their side and try to sleep. He was pleased to see that his poultice was working. That their HP ticked had up a couple points, though five whole points was just a drop in the bucket. Obedient, the human tried to lay down, movements stiff with exhaustion and pain. Standing, Gaster looked to Grillby. “That’s information, at least. The mages are desperate for healers, and for help.”

“The mage I killed must’ve been the one to do that, then.” Grillby nodded to himself. “What do the runes mean?”

“We’ll ask them tomorrow. I have to change the bandages and dress the wound again.” They both nodded.

Evening passed quietly into night. A handful of monsters wandered their way to the elemental, asking him to explain why they had a human in tow. He tried his best to get them to understand. A couple did, but most didn’t. When dinner was finished, he realized that the human may need to eat. Gaster agreed. They ladled the remains of the stew into a bowl and helped the human sit up. Cursing, he had Grillby hold them up. The human protested at being fed—they stated that they aren’t a child—but when they tried to bat him away, the movement made them curse and cringe. Their forehead glistened with sweat again, and he saw their HP drain another point. After Gaster thwacked them with the spoon and quietly whispered about how little health they had left, they sat still and let the monsters feed them.

They seemed to sink into Grillby’s warmth, too tired to do much else. Satisfied that he’d kept them from dying a little more, he and Grillby lay the human back down to sleep. Before their eyes closed for the night, he quietly asked, “What’s your name?”

“My mother named me ‘Lily,’” they mumbled, “but the hedge witch called me ‘Cooper.’”

“Alright, then. Good night, Cooper.” _Don’t die_ , he added, knowing he wouldn’t get any sleep that night.

 

When Gaster woke up the next morning, he could smell that it had rained. There was no need to open a single eye socket to see that was the case; snow left a distinct crispness to the air that was tangible. And this smell was not that. Sleeping beside Grillby in their tent, he didn’t want to move. The elemental’s natural body heat kept him comfortable, despite the seeping coldness of the floor. He could feel the sinking wetness trying to descend into his bones.

He didn’t want to move, until he heard the cough. Pushing himself up, he saw that it was just before dawn. It took him a few seconds to realize who had coughed.

The human—Cooper, he reminded himself—was curled in a ball at the edge of the bedroll. Their cloak was frosted, the wet blood from yesterday turning pink. And it had slipped off their shoulder, covering almost none of their back or torso. Mere bandages sat between them and the chilled, spring air. Cooper coughed again, a wracking, full-body cough that wrung the air from their lungs. He pushed himself up, his movements waking up Grillby, who unfurled and stoked himself into oranges and yellows.

“They’re alive,” the elemental said, as much a question as a statement.

“Only just.” Once again, he checked the human’s HP. It was still low. Last night, when they fell asleep, they had four HP. Now they had six. Two HP over the course of the whole night. Lightly cursing his forgetfulness, he dragged his blanket over to Cooper and wrapped it around them. Tying it under their neck, he replaced their cloak and sighed. As Grillby stood up and stretched, Cooper coughed again. His charade needed to continue, at least until Gaster was satisfied. Composing himself, he pulsed in waves of yellow and green flames as he walked towards Cooper. Gaster looked up at him. “I forgot how little we feel temperature.” Grillby crouched by the bedroll. If heat was all the human needed, then he could oblige. He put his warm hands on the sleeping human’s forehead. They seemed to relax a bit, the heat of his presence a comfort, at least. “Especially when you share your tent with a fire monster.”

“Can they walk?” he asked his friend. The doctor looked skeptically at Grillby and shrugged. “I doubt it.” With a smirk, he added, “You may have to carry them again.”

He _really_ didn’t want to. Something about carrying the human made him remember the little mage who’d held back a whole river to protect him. Those emotions weren’t useful to him. With a sigh, he acquiesced, “At least I don’t get tired.” He watched the smoke billow out from his mouth, turning to a puffy breath in the snowy chill.

As the elemental stood, Gaster said, “The runes on their back are probably hindering their healing.” The look on Grillby’s face told the skeleton that he didn’t understand. “Rowan,” he added, “the barrier spell drew power from his soul. I’m betting this is the same.”

“What can you do about it?”

“I don’t know much about runes—they mages I’ve seen have spoken their spells, not written them. Maybe in books, but not onto things. Except for wards.” He paused, contemplative. “Maybe this is like a ward—whether it works is hit or miss, and it needs specific situations for it to apply.” With a sigh, he admitted, “I only know what you told me, though.”

With a shrug, Grillby said, “Maybe when we’re back at the fort, Thetis will know.”

Gaster took a deep breath and let it out slow and calming. “We’ll figure it out eventually.”

Standing, Grillby put a hand on the skeleton’s shoulder. He smiled, and said, “I know you will.”

The elemental then went off to shout hoarse insults at his soldiers, waking them up and telling them to grab a quick breakfast before the second day of marching began again.

For all the commotion going on outside the tent, Cooper slept soundly enough. When they coughed it made Gaster worry that another point had dropped from their meager total. He woke them up just before Grillby collapsed the tent, helping them up and bundling them with as many pieces of fabric as possible. That, at least, seemed to amuse them. “I’m fine,” they mumbled as Gaster put a fifth blanket over their shoulders before helping them clasp their cloak.

“No, you’re not.” With a frown of displeasure, the doctor explained. He asked them if they really didn’t know anything about the runes.  

Another bout of coughing all but knocked them over. “I don’t know many,” they managed. He huffed his approval and set about finding an extra pair of shoes from _someone_. Because when he’d touched their feet, he thought his fingers would freeze and turn into icicles.

A fluffy monster offered their own. “It makes my fur damp, but I’ll manage.” Thanking them, Gaster returned to the tent, boots in hand. They were quite big—it looked as though Cooper were a child wearing their parent’s shoes. But it was better than walking around in snow.

After they collapsed the tent, Gaster slung an arm around Cooper’s waist and helped them walk. He felt every breath of theirs, every cough that wracked their lungs. Until they stopped for a quick lunch break at midday, they walked fine with his help. The exercise even seemed to put them in better spirits. Even if it did seem to wear them out, make them breathe more of the chilly air, make them cough more. After stopping, it was hard for them to stand back up. Gaster checked and although their HP hadn’t dropped, their energy level was fading. And fading fast. Any deep breaths they took were forced out by more coughs. As they sat, it seemed pools of liquid built up in their lungs. The dry coughs had become wet, hacking things, full of phlegm and misery.

“I’m fine,” they said for the umpteenth time that day.

Gaster looked at Grillby, who knew he’d have to honor his words. Inside, he cursed at himself. For deciding now was the time to prove to the skeleton that he had empathy. For deciding to help carry the sick child back to the fort. For deciding to be nice to them at all. As he picked up the human, the elemental heard a murmur from the surrounding monsters. Gaster himself gave a chuckle, and made a quiet comment about Cris. For a second time that day, a fondness sparked through Grillby, his fire turning a bit purple and blue. He didn’t want those feelings. He didn’t want to think of Cooper in that way, to feel for them, to want to help them. He didn’t want to be reminded of his own inconsistencies.

The afternoon was peaceful. At some point, Cooper had fallen asleep. They curled in, towards his core and the warmth it brought. Sparks of blue blazed in him; he felt an odd sense of calmness with the little human in his care. It fought past his own reasoning. A worming, creeping thing, that set in slow and heavy in his soul. To Gaster’s pleasure, their coughing lightened, the wateriness dying down as the day wound down to an end. A light snowfall began just before they broke for camp.

Whipping his core warmer, Grillby released a swooping arc of magic, clearing out the white blanket. His soldiers gave him quiet thanks as they began setting up for the night. From his arms, he heard Cooper stir with a cough.

They blinked tired eyes up at him. He couldn’t help but smile back. Despite everything, he’d started to like this human.

Setting up camp worked the same as before. Except this time, Cooper was awake and garnered more attention from curious monsters. Grillby set them down next to a cooking fire as he prepared a huge pot of stew for his soldiers. Their pallid face took on a healthy warmth as they relaxed there, watching the elemental go about the motions. Though he complained about it the whole time, Gaster put up the tent. Another batch of medicine prepared, the elemental helped Cooper to the tent and left the doctor to his medicine and questions.

As the last of the stew was ladled into bowls, Grillby sighed. It was odd to feel so content when around them waged a war. So odd, especially when he didn’t quite understand why he felt content. When he’d seen Cooper in the forest, he’d told himself not to think of them as a creature. More like an obstacle, something in the way of his goal. The thought of Gaster’s displeasure—the possibility of losing his friendship with the skeleton—was the only thing keeping him from tossing Cooper to the side of the road. Yes, he told himself. There was still that steely personality somewhere inside his core. He told himself this, but in the back of his mind, he knew he would never actually go through with his thought. Did it make him horrible for even thinking it?

 Disquieted, he swallowed up the cooking fire, walking two bowls of stew over to the tent. Gaster greeted him, Cooper patched up and holding onto the last legs of consciousness. If they gentle sway of their body and the dipping of their head was any indication, they needed to sleep. And tonight, Gaster let them eat on their own.

Once they’d finished, the doctor fussed for a while, piling blankets higher and higher, before they drifted off. He checked their HP one last time, grinning to himself. Even with the coughs, they had seven HP, and the skeleton could almost feel it ticking up to eight.

Grillby tried not to feel hopeful for the human. But he did.

**Notes for the Chapter:**

> So! As with most things I write, I don't usually write chapter-by-chapter... Instead I write everything in one big, long blob and then figure out how to chunk things up later.
> 
> This means that sometimes chapters are wildly different in size...
> 
> In any case! This chapter and the next few were fun to write, though (in my opinion) the direction of the story was harder to hone in on in later chapters. Hope you like it!
> 
> And if you haven't, go read Casting Rain! It's here: https://archiveofourown.org/works/6119951
> 
> Without it, you're probably just a tad bit lost. 
> 
> Don't worry. It's a quick read. It's only 70 chapters, anyways!! >:)


	3. Repetition and Recovery

**Summary for the Chapter:**

> In which the human starts feeling better... and shit goes down.

The next day worked in much the same way, except Gaster insisted on Grillby helping Cooper all day. “The warmth will do them some good, firefly,” he told his friend. For Grillby, it was a small annoyance, but he acquiesced to the doctor’s orders. As they marched the disappearing miles away, the skeleton signed to himself, deep in thought. From the corner of his eye, Grillby could understand some of the gestures, but the entire conversation was beyond him. Instead, he listened to his soldiers’ conversations drifting towards him on the breeze, and Cooper’s hacking coughs. As was the case the day before, after a lunch rest Cooper could barely walk. A bit more than before, but not enough to get back. And again, Grillby carried them. After an hour passed of them curled in his arms, he heard them mumble, “Why are you so nice to me?” Their eyes flickered shut and they were asleep before the elemental could even respond.

He shot a questioning glance towards the skeleton, who didn’t seem to catch what they’d said. When he asked Cooper to repeat themselves, they mumbled it, still on the border of consciousness. Gaster smiled and nudged his friend. The two of them looked at each other, and Grillby had to admit that he _was_ being quite nice.

After a few more hours of marching, Grillby could see the faint haze of fires on the horizon. A distant horizon, yes, but there. When they crested a hill and the soldiers saw the safety and relative peace of their home, a cheer went up. They camped there, the whole party a much more lighthearted band than before.

As before, Grillby went off to make some dinner from the meager rations they carried. Gaster stayed at the tent, watching Cooper sleep, thinking. So deep in thought, he didn’t notice them rouse and push themselves up. They coughed; he heard it through the fog of his own thoughts. It reminded him of feet stuck in the muddy banks of a river, the wet, viscus stuff slurping at his feet and sucking him down. Sticky, wet.

Leaning forwards to support them, he asked, “Can you breathe alright?”

“I’m fine,” they intoned, sucking in breaths of cold night air.

“No, you’re not.” He sighed. Either they weren’t taking him seriously—which was ridiculous, since he _was_ a doctor—or they weren’t taking their health seriously. “Trust me when I say that.”

They doubled over coughing, hands clutching their chest in pain. “I’ll get better.”

“Not fast enough.” A flicker of a thought shot through his mind. Remembering his inventory, he pulled out the books he’d grabbed from Thistle’s tent before Grillby had burned everything down. “I… acquired… these a few months ago,” he said, showing them to Cooper. Surprised, they leaned in towards him with interest. He rifled through the pages, pointing at one. “What does this mean?” As they blinked and looked over the page, he began pulling bandages from their wounds.

Wheezing a bit, they read the page aloud. “Ice: can be used in combination with runes to specify placement, appearance, structure, or scale.”

The doctor flicked through more pages, landing on another rune he saw. “And this?”

“Winds: specifically, that of high winds. Temperature is moderated by the air surrounding the caster.”

He pulled the last of the bandages off, then turned a few pages. No other runes matched those etched into Cooper’s skin. So, he pulled the second book out, leafing through those as quick as he could. “This one, too.”

Seeing the books, and the agitation on Gaster’s face, Grillby walked up to them. A quizzical look rested on his face as he recognized the rune the doctor pointed at.

“Storm: will create any type of storm the caster chooses. Strength is determined by caster’s will and intent. Longevity is determined by a caster’s fortitude. Needs additional runes to generate specific types. Otherwise, rain, thunder, and lightning are generated.” They coughed, looking to Gaster. “These are the ones on my back?”

“They are.” He felt Grillby’s warmth and he turned, relaying what he could to the confused elemental.

“If runes are broken,” Cooper coughed, “they won’t work.”

A spark of something flickered in Gaster’s eyes. “Come again?”

Heaving in a deep breath, Cooper explained, “Anyone can use runes. You just write them, or draw them, or… carve them down and they do their thing. Mages speak them, but that’s different. That’s the old language. That’s magic. But written runes have their own power.” They looked at Gaster. “If you break the runes, they won’t work anymore.”

Grillby looked confused, looking to the doctor for explanation. “It’s not on paper. We can’t rip them up, or break the stones they’re carved into.”

“Even a single mark out of place will render a rune useless. So, if you marked them all up, they’d all stop working.” They took a steadying breath. Cold determination rested on their eyes as they said, “Cut them up.”

“What?” Gaster pushed the bandages aside, aghast. Shocked, Grillby looked at him. The skeleton’s hands were going a mile a minute.

It was all the elemental could do to put his hands on Gaster’s arms and calm him down. To make his friend look him in the eye. “Just breathe. Will it hurt you more?” Cooper stared straight into his eyes and nodded.

The skeleton took in a shuddering breath and sighed. “We could try to minimize the damage, but it’ll still be painful. Cost you some HP. And you’re already so low as it is…”

“Do we know if this’ll stop it?” Grillby felt the hopefulness in his chest rising.

Shrugging, the skeleton said, “No, but it’s a good shot.”

From where they sat, Cooper asked, “Does it have this rune?” They’d pushed the books aside, drawing out a curling rune into the dirt. The lines spiraled in a tight oval, sprouting forth to billow out in whorls and elliptical shapes. Cooper’s drawing looked more like a sprouting seedling than a word or a spell. Gaster nodded. “This one?” In the dirt they drew another rune, a simple spiral with four lines, crossed two by two, in its middle. Gaster nodded again. With that, their shoulders drooped a bit. “The first means to connect to life, the second death.”

The skeleton stood still. He understood what the kid was implying. “Kid, you can’t be serious.” Grave, they nodded. “The spell builds strength as they live, and will cast when they’re dead,” he informed Grillby.

The elemental winced. “The longer we keep them alive…”

“The stronger the ice storm will be.” Cooper nodded, solemn. And calm. It almost shocked the elemental to see how little the news of this affected them. Nothing in their face betrayed sadness or terror. Their eyes, though, seemed to flicker with a bit of darkness.

“As it goes, how long do you think…?” Yep, he definitely started to care for the human. How was it so easy to change, when he’d been so deep in anger?

“At the best?” Shaking his head, Gaster dislodged his arms from Grillby’s hold. “A week if their cough worsens.” Blues and greens whipped through the elemental’s fire. “It’ll cast when we’re at the fort.” Crestfallen, the doctor looked down at the kid. “And at worst, it could cast tonight.”

“Do it,” they said. “I’ll be fine.” As they pushed themselves to their feet, the blankets atop them dropped to the ground. They staggered forwards, careening towards Gaster. From his belt, they pulled a dagger—one Grillby gave him for protection. They held it out in the air, hilt towards the two monsters. A pleading expression pained their face. “Please,” Cooper breathed.

Grumbling, Gaster took the knife. “You’re going to help me, firefly. I might need your magic to stabilize their soul after this.” Hooking his arms underneath the blankets, he picked them up. “To the fire. Just in case of ice.”

Grillby nodded, wrapping his arm around Cooper. Despite the gravity of their suggestion—no, plea—they seemed happier. A sudden thought ran through Grillby’s mind. Perhaps this was all an elaborate ploy? To send a human out, magic written in their skin. If the monsters killed Cooper the moment they laid eyes on them, the spell would’ve wiped them out then. If they delayed longer, eking out the last few days they had left, the spell could’ve wiped out the entire fort. Even now, as he pulled them along towards the fire burning bright in the snowy night, the spell could take out the whole camp. He flickered in worried greens and yellows at Gaster.

The skeleton mistook his worry for his soldier’s safety as worry for Cooper. “We’ll do our best to keep them alive, firefly.”

“What if…” he said, setting Cooper down beside the fire, “this is a trap?”

Dropping the blankets to the ground, he tucked them around the human. They clutched one to their chest, their back bare and pale in the light. “If anyone could devise a trap like this,” he said, “then it would be the humans.” With a groan of frustration, he added, “If it is, then you can haunt me ‘til I die.”

“It’s on your head, then.” The elemental put his hand out, gesturing for the knife. He stuck it on his hand, heating it up until it burned a bright white. Not enough that it would melt, but enough that it would seal their wounds. He may not be a doctor, but he knew that much. “Here,” he mumbled, handing it back to Gaster.

The skeleton steeled himself a few steadying breaths. With that, he leaned forwards, putting a gentle hand on Cooper’s back. The white of his fingers stood out against the angry red patches. “On three, okay?” Clutching the blanket further, they nodded. “One…” Gaster said, readying the knife in his hand. The heat from the blade seemed to cut the air around him. Cooper leaned forwards, putting their head into the blanket. “Two.” He took a deep breath. The knife hovered less than a hand’s width away from their skin. They took a deep breath, readying themselves. Without even saying three, Gaster cut into their skin.

Through gritted teeth and fabric, Cooper let out a strangled cry. The smell of burning flesh rose from their back as Gaster pulled the blade from one side to the next, cutting just deep enough into the flesh to score a steady line through the runes. They started to shout, a scream that ripped apart the stillness of the night air. He paused in the middle, skipping over their spine, before returning to his work. Finished, he dropped the knife down onto the snow. Whatever heat was left on the blade melted the flakes into a puddle. The fire hissed. Cooper let out a sob, collapsing to the side, the fire illuminating the blood pooling at their side.

For a second, nothing happened.

Then, as though materializing from the cracks in their flesh, through the blood pouring out from his cut, Gaster saw magical ice and smoke rise. The magic coiled into the air, a great cloud forming above them. A peal of thunder wracked through the little camp. Monsters looked up in horror, smelling human magics, feeling its presence in the sky, and cried out. Chain lightning lit up the clouds forming as flakes of snow and balls of hail began to fall down to the ground.

Looking at his friend, Grillby wanted to simultaneously yell at him ‘I told you so,’ and scream in fright. The cloud grew overhead, building from the pain and life left in Cooper’s soul. Gaster pulled their soul out, untangled it, and rushed to fix the blood leaking from the gashes he created. It wasn’t enough. It couldn’t be enough. Buckets of magic poured from their soul, sloshing up into the sky to create this wheeling, whirling vortex.

Bitter winds swept through the camp in a spiral, small pieces of ice biting into Grillby’s fire. Gaster gritted his teeth, pulling Grillby’s soul out. A glowing thread followed his fingers, looping itself around Cooper’s soul.

The elemental could feel it. He could _feel_ the green-ness of their soul. He could feel the caring they had, the desire to help, to heal. The burgeoning, familial love they had for the monsters, the melancholy they felt from being away from family. The pain of it all. Oh, the pain. It almost whited out every other feeling within them. The little HP left in Cooper’s soul drained. A crack formed in their soul, radiating out from the center. The trail of magic from Grillby’s soul snapped and disappeared.

Cooper’s soul shattered into small pieces in Gaster’s hand. The pieces hung there, the last vestiges of their life. It would dissolve into nothingness in a minute or two, and any hope of theirs would be lost.

But it didn’t. It refused.

Shaking, arms quivering from the weight of it all, Cooper pushed themselves back up to a kneel. The shouted again, a pained hoarseness scratching through it all. The billowing magic slowed, stopped, and released its hold from them.

In an instant, the lightning shot itself out, the light dissipating. The wind slowed and stopped, any ice it once held turning into nothingness. The cloud collapsed on itself, imploding in a glorious whirling of ice and magic.

And, just like that, it stopped. Particles of left over magic scattered down from the sky, tinging the world in its odd, tingling smell. Shaking, Cooper turned to smile at the two monsters. “I couldn’t let it kill you,” they breathed, collapsing onto the blankets, hanging onto it all. “I couldn’t let it… You were being… so nice to me.”

Gaster scrambled, pulling theirs and Grillby’s soul out to stitch the human back up. The bleeding stopped, he washed and cleaned their wounds again, all the while silent. Grillby stared, blinking at them.

In all his days, he’d only seen that once before. The redness of Thistle’s soul, coursing with angry determination, flickered in his mind. But Cooper’s soul was green. Healing and health, not hellfire and destruction. And yet, it refused.

The furry monster who’d lent Cooper their boots walked up, shaking a bit. “Commander, is it coming back?”

He shook his head. “I don’t think it will be,” he whispered.

Sitting back on his heels, Gaster sighed. He dispelled the magic thread from Grillby’s soul, and gave his friend a shaky smile. “They’ll live.”

The rest of the night was spent consoling worried soldiers and reapplying Cooper’s bandages. Most were genuinely concerned that …that would happen again, that the spell could erupt from their back at any moment, whipping into a frenzy of rain and ice and wind. The two monsters did their best to dispel any concerns. One or two even asked if the human would die. To that, Gaster shrugged. “Not if I can help it.” Back in the tent, he set Cooper’s head on his lap, brushing their hair from their face and checking their HP every few minutes.

Cooper slipped in and out of consciousness throughout the night. The whole ordeal had taken a lot out of them, and their HP wasn’t looking well. Gaster was concerned that they wouldn’t last the night. With a resolute, but sheepish, grin, Grillby stationed himself right next to Cooper, radiating as much heat as he could without setting fire to the blankets. Gaster sat in an exhausted vigil, once or twice nodding off, only to be roused by their coughing.

The next morning was terrible. At first light, Grillby sent off a messenger to inform King Asgore that they had a human captive in hand. As the march began, mumbles from the monsters behind them spoke of the winds brought about by Cooper’s spell discharging. But these were not the same biting winds. Clouds from the west moved in with rapid speed, bringing with them chilling rain and slush. It sunk into the ground, turned well-trod paths into puddles of dirty ice, and made everyone cold and wet and uncomfortable. Just enough to irritate, but not enough to hurt.

Unless you were a sick human recovering from a major injury. Though Cooper tried to stand and walk on their own, it was obvious that they needed support. The cough that wracked their body did not go away in the night—despite their best efforts, it deepened. To the point where if they coughed, they doubled over clutching their chest. Leaning on Gaster for support, they wheezed until the hacking stopped. It wasn’t even ten in the morning when Grillby marched over and unceremoniously scooped the coughing human up in his arms.

His radiating warmth did help dislodge any phlegm stuck in their lungs. After lunch, they began hacking up large clumps of mucus. Which was disgusting, for everyone involved. Cooper hated the feel of it. A heinous mixture of sticky and gooey, it seemed to clog their wind pipes and ooze from their throat. Gaster hated the look of it. The clumps were the color of golden flowers, gritty and transparent and shiny. Grillby hated the sound of it. The dense sound of Cooper’s coughs, the hawking sound of the phlegm rising in their throat, the goopy sound of it hitting the ice and slush-covered ground.

The soldiers did their best not to step in it.

By mid-afternoon, they were within distance of the fort for Grillby to grow worried. Though they’d sent a messenger ahead, for all he knew, King Asgore would want the kid thrown in the stockade. Or he could put them under house—tent? —arrest, never to leave the infirmary. Or he could keep them as a sort of disturbing pet. Or make them a training exercise. Or he could just kill them.

In his gut, his emotions twisted in knots. Beside him, Gaster tried to be jovial, to talk about fun and interesting things. Cooper seemed excited to get back on their feet and try helping the infirm. Both discussed medicine at length, Gaster team humoral medicine and Cooper team disease. Though it was hard for the human to speak much at length, the two tossed back and forth arguments that Gaster happily explained, to Grillby’s amusement.

The kid wasn’t a push over, that’s for sure. The light in their eyes sparkled when discussing old patients and newfound methods to cure the sick or wounded.

As they crested the last hill before the fort, Grillby paused. Standing at the edges of the monster encampment were sentries. He could see Terros, with his stone arms crossed. He could see Thetis, holding spears in her hands. If he were close enough, he could differentiate the other monsters clustered at the edge.

The commander could feel his soldiers shift awkwardly behind him, awaiting orders. All of them wanted to be there, to be somewhere safe and comfortable. Even Grillby thought of the fortress as home, thought of the monsters there as home. The safe, steady atmosphere was tugging him forwards. He looked at Gaster, who signed at him, sharing his own flavor of worry. Passing Cooper to him—Gaster did not hold the human, but instead propped them up against his shoulder—Grillby turned and spoke to his men. “What’re you all doing, lollygagging around?” Some jumped at the roughness he forced into his voice. It even grated on him, a tickling reminder of Amathea, of mages with unspeakable power. “Get back to camp, set up yer tents. You’ve got one hour from now to relax. Meet me by the training grounds at hour’s end, or you’ll be digging latrines ‘til midnight!”

To his amusement, his soldiers scattered. Some ran, others walked, and a couple sidled on towards the fort. He and Gaster hung back with Cooper, the last ones through the little blockade of sentries.

“That’s the human,” Terros said, looking at Cooper’s hobbling form, bloody cloak, and tired expression.

“That’s the human,” Grillby repeated in answer.

Frowning, Terros said, “King Asgore wants to see you, now.” Flicking a look to Gaster, he added, “Your messenger let us know that the human is… unwell. The king wants them to stay with the two of you until they’re healed. Then he wants to speak with them.” Turning away, frown furrowing deeper into his rocky face, he led Grillby towards the heart of the camp. “He’ll decide what to do with them after.”

Hefting them up to stand on both feet, Gaster looked at Cooper. “Let’s go set up the tent.”

It took them ages to actually do that. Cooper was not much help at all, save for sitting down and hammering in stakes. While Gaster tried to do it, he just didn’t seem to have enough force behind his swings to even break the icy surface of the grass. For what it was worth, Cooper thought his weakness was amusing. “At least I’m not the only one who needs help,” they whispered, more to themselves than to him.

A fire took some coaxing to bring to life. Though it would’ve been easier for him to wander off and collect firewood himself, there was always a watchful eye on him and Cooper. Instead, he borrowed some firewood he just so happened to find, piled in a neat stack. It was a bit damp, but after the smoke cleared the fire roared to warmth.

He sat Cooper there, piling blankets onto their shoulders as he finished setting up the rest of things for the evening. The hour Grillby promised came and went; seeing as how he didn’t come back to their tent, Gaster had no way of knowing whether or not the fire elemental was able to hold his soldiers to his promise. That is, until he saw a couple grumpy monsters he recognized, hemming and hawing as they trudged downhill, towards the edge of camp.

Cooper did well, trying to stay awake until Grillby came back and started cooking. Their eyes flickered closed a few times, only twice did they fall asleep for a minute or two before Gaster prodded them awake. When they could hold their eyes open no longer, Gaster pulled them inside the tent, closed the flaps as far as they would go, and reapplied his healing salve.

With it being so early into the spring, his store of herbs was dwindling. The two discussed options for other salves or tinctures before Cooper started to drift off, sitting upright but listing to the side. Satisfied that their wounds were clean and treated well enough, Gaster listened to their lungs. He placed the side of his skull against their back, instructing them to take deep breaths.

It was uncomfortable for him—he had to collapse upon himself to even reach them while they sat—and awkward for Cooper. Never once, in their life, did they have someone crouched on the floor, hands on their ribs, listening intently to their lungs. “You need something dry to help clear up the overabundance of wet humors,” he said, looking at his box of herbs without luck. “Maybe there’s a vendor somewhere,” he added, “Grillby could have some, too. If his spice box hasn’t run out.”

Shaking their head, Cooper explained, “It’s an infection. Some tiny disease that’s worked its way in. I just need rest, hot foods, and something to help me cough it all up.”

As Grillby pushed aside the tent flaps, surprised to see them drawn at such an early hour, he smiled when he saw Gaster and Cooper discussing remedies and curing methods. “Grillby!” Gaster cried, looking to his friend. “Be our tiebreaker. Cooper here thinks they just need something to get the phlegm—”

“Mucus,” they interrupted.

“—what have you, the ‘mucus’ out of their lungs. I, for one, believe they need something to dry out the phlegm, as it is _imbalanced_.” He looked at Cooper with a stern stare before his gaze returned to the elemental. “What say you?”

“I’m… not a doctor.” Grillby sat down near the two, his back to the open flap. Cold wind rushed in and Cooper tried to cough quietly. It didn’t work. “But, can’t you do both?”

With a start, Gaster looked at his friend in a new light. “That… could work.” A smile returned to his face. “Another quick question—do you still have any spices left?”

Grillby pulled the spice box from his inventory, surveying its contents with a sad look. “It’s empty. Been empty for a few weeks now.”

Sighing, Gaster stood. “And I have no appropriate herbs to dry out your cough, kid.” He strode over to his boxes of herbs, looking them over. “What would you have me prescribe to… expel the phlegm?”

“Well, to get the mucus out, you’d need a root like lungwort.” They paused, thinking. “Or lobelia, or horse-heal. And a warm compress could help, but it won’t stay warm through the night. Maybe tomorrow…” They stifled a yawn, slumping a bit towards Grillby’s warmth in the process.

“I’ve got horse-heal and lungwort. But I need to find some lobelia next summer…” Looking back at them, he sighed again. “You need sleep,” he said, walking over to pull blankets onto them, “that, at least, we can agree on.” Satisfied, they closed their eyes and within minutes they were asleep.

As Grillby watched, trying to follow the conversation as best he could, he had to marvel a bit at how easy it was for Cooper to talk to Gaster. Everything Gaster had told him, about the potions and tonics and tinctures and balms and infusions, went over his head. The magic his friend showed him, the concentrated dismantling of souls to string back together, was just a bit too alarming for him to pay much attention to. Despite knowing that Gaster could handle it, Grillby wondered what the long-term ramifications could be if the doctor somehow got it wrong.

Looking up at his friend, he sighed. Steam curled from his lips as the heat hit the water in the air. “I wasn’t built for this kind of nonsense,” he grumbled.

“What nonsense?” Gaster asked.

“This…” he gestured at the half-awake form of Cooper. “Caring for someone. Making sure they’re safe and healthy, those kinds of things.” Looking at his hands, he added, “I was summoned for to kill.”

“You were summoned to kill _mages_ ,” Gaster said, pulling Grillby up and dragging him outside the tent as he made a horse-heal and lungwort infusion, “and they’re not a mage. They’re just a human. And they have no LV—you must’ve seen it for yourself. They heal, not hurt.”

“How do you know they’re not a mage? They smell like magic.”

“The magic ingrained in their back, perhaps.” The skeleton looked at him and frowned. “If the human _had_ magic, they would’ve used it at a moment’s notice. Tried to take you down before you stabbed them—”

“I didn’t stab them…” Grillby muttered.

“Yes, you did. It just didn’t kill them.” Gaster set a small pot of water on to boil. “Wouldn’t they have done something by now? To fight back, or to heal themselves?”

“I guess…” he said. In silence, he watched as Gaster threw the pieces of dried roots into the simmering pot. “But what if they are? And they’re hiding it? I’ve been summoned to kill mages. Wouldn’t I have to kill them, then?”

As he stirred the pot, Gaster shrugged. “It’s not up to me, firefly. We could’ve killed them ten ways to Sunday in the first hour of knowing them. You’ve seen their HP. Even I could take them out in a heartbeat.” He looked over the fire at his friend. “It just… depends.”

“Depends on what?”

“On whether they try to hurt someone. If they do, then you’ll know. And if they don’t, you’ll know then, too.” Staring at the green and yellow flames, he added, “It’s something you have to know then and there.”

“I guess…” the elemental mumbled again. A few days ago, he would’ve shot the human down without a second to think. A few months ago, he would’ve saved the human and kept them away from the fray. Now he was doing neither. Though he hadn’t killed Cooper, he wasn’t exactly keeping them safe by bringing them to King Asgore.

The two sat there for a while, Gaster busy at work while Grillby contemplated the fire. After a while, the elemental pulled out a cooking pot and set to work making supper as usual. His motions seemed calculated, though. As though his mind were focused on something else, his body working on instinct instead.

Once Gaster was finished, he popped into the tent to wake up Cooper and administer the medicine. He came back smiling, saying that the infusion had “tasted disgusting,” and that, “they wouldn’t drink it unless it was to spite him.” It made the elemental smirk, and that was enough for him.

They slept near Cooper that night. Grillby lay in the middle, radiating warmth that the other two gravitated towards. It had been a while since his back felt warm. Since Amathea died, there was just Gaster, whom he kept in sight. It was terrible, after nightmares, to wake and see the skeleton gone. To think he was gone. To be convinced he wouldn’t come back.  So, he kept his eyes towards Gaster, his back on the rest of the world. It was nice, feeling a body there. It had a kind of balance to it. His dreams were full of bawdy laughter, mesmerizing songs, and dust.

**Notes for the Chapter:**

> And as we can see, the methodology of my chunk method isn't quite... well... even. This is the longest chapter by about 1k words, which isn't much for me, but it might be for you. Not going to lie, posting such long chapters on here feels a bit tenuous at best. Most chapters I've seen fall in the range of 1k-3k? Or perhaps those are just the fics I read. So... 5k feels a bit like a stretch. But hey! It's not 5k. It's 4.9k. Yeah, 'cause that makes it better.
> 
> I had this image in my mind since the moment I wrote it, so it was seriously rewarding to write it all down. That being said, it heavily relies on narration and description. Which may be my wheel house, but it's also tedious to read and write at times. But oh well!
> 
> The whole image of this was exceptionally fun. I had a clear picture, and getting that picture across took a lot of writing and rewriting. Hopefully, I didn't fall into too many cliched pitfalls. 
> 
> The next chapter after this is mostly wrapping things up. It's the one I'm the least confident in. Then again, I was always terrible at conclusions. Just ask my 6th grade science teacher. Essay? Wonderful. Conclusion? You are the weakest link; goodbye.


	4. An Ending

**Summary for the Chapter:**

> In which it is revealed that I, dear reader, am also a sap. IE: a happy ending if there ever was one.

Things weren’t perfect. But they got better. There was a newfound contentedness and energy in Gaster that the elemental knew he’d not seen in many months. Not since his confinement in the human fortress, he guessed. The excitement and vivacity he had for healing had returned. On days where Cooper was confined to the tent, they discussed the virtues of liniments, of mixtures with different ratios of herbs and roots. Of wound care and of diseases and of humors.

On the days when they could walk about the camp with one of the monsters as escort, Gaster beelined to the infirmary tent with them in tow. Always ready to help, they held a hand or paw with a soft expression and quiet words. Many of their patience seemed better, healed well, and felt less hopeless. There was less dust in the tent, when they and the skeleton were involved.

While his soldiers ran around finishing chores, Grillby wandered his way to the infirmary tent, intending to look in on the two. He saw Gaster, flitting about and applying salves and compresses. The human forces were closing in, pressing the monster forces west towards Ebott. Some companies hadn’t been lucky. There were always wounded soldiers cycling in and out of that tent. A few beds held nothing but dust. He tried not to look at those, not to think about those lost souls, tried not to remember what it felt like to have dust seeping into his armor.

He couldn’t find them. After scanning the beds from his spot, one of the nurses walked forwards, intent on chasing a gawker from her tent. She huffed and puffed at him for a bit. Jokingly, Grillby replied, “I’m not a little match that you can blow out.”

The nurse let out a dark laugh and said, “Don’t try my patience, Commander. Why’re you here, elemental? Been keeling over in a faint again?”

“No, I’m fine.” Looking around the tent once more, Grillby asked, “Where’s Cooper? Uh… the human who came with Gaster.”

With a nod, the nurse pointed towards a cot. “They’re over there, helping us look after a poorly monster.” She pushed him in the direction as she began her own rounds.

Once she’d pointed out Cooper’s coppery hair, he could pick them out from the blood-stained brown cots. They were kneeling at the side of one cot, their hands steadied on the monster. For what it was worth, the monster didn’t seem to notice they were being helped by a human. It would be better for them to stay unconscious for a bit.

Walking over to them, a breeze whipped through the tent. Grillby smelled the particular tang of magic in the air. This wasn’t the metallic smell of Gaster’s magic, or the acrid smell of the magic in Cooper’s back. What hit him was an earthen scent, one of new growth and flowers. He took a step forward, looking outside to the trees. For a second, he almost couldn’t believe that it was magic, and not the call of spring. But it couldn’t be—the trees were still barren and covered in patches of snow. Any growing greenery would have to fight through the nightly frosts to flavor the air. He took a step forward.

Then, he looked around. A monster must be using their magic to heal. But he didn’t see the telltale sign of glowing green magic anywhere. The nurses and doctors were bandaging wounds and administering medicine, not actively healing. He took a step forward.

He paused behind Cooper, the scent stronger than before. A tightening in his gut told him to ignore his hopeful delusions. Told him to trust his instincts. Told him to just look. So, look he did.

As they knelt beside their patient, the palms of their hands glowed a soft, discreet green. The expression on their face was one of intense concentration and frustration. Their lips moved quietly, forming whispered spells and incantations. Despite everything, blood mixed with dust leaked out of the wound. The last soldiers to arrive had been _days_ ago—if the monster was still bleeding like this, they must’ve lost hope. They were falling down from listlessness. Green magic surrounded Cooper’s hands. Grillby wasn’t versed in magic, but if he knew one thing, it was that green magic always healed.

Cooper was trying to help.

But Cooper was a mage. He was _summoned_ to rid the world of mages, to protect the monsters under his command from human spells, incantations, from their damned runes. He was obligated to destroy any mage he saw, like he’d done so many times before. Images of Thistle, their soul refusing out of sheer determination, flashed through his mind. He saw the mage with that blinding white magic, felt the echo of force like a wave through his body, the dust of Amathea on his flames, the seeping sand of Ora in his mind. He thought of the white-out that nearly destroyed Gaster, turned the skeleton into a whirlwind of nothingness. The magic that stripped him of his friends, of his allies, of the things that made up his whole _world_.

And he saw Cooper, still kneeling at the monster’s side as they fell. He saw Cooper, crying out in exasperation as their hands tried to clutch the dusting monster. He saw Cooper, silent tears falling down their face as the dust in their hands dropped to their lap.

And he saw Gaster dash forwards, a look of sorrow and of horror on his face.

Only then did Grillby realize that he must look terrifying. If he had a neutral tone, it was that of yellows and oranges. They were happy, warm colors. It made others think of the sun, or of gold, or of flowers. Now he was full of the harshest reds, accented with shoots of white and pale blue. He was literally red-hot. Peaks of purple and white burned from his head and shoulders.

He felt more than noticed the sword gripped in his hand. He felt more than noticed Gaster putting a hand up to stop him. He felt more than noticed Cooper turning around, fright turning their face paler than usual, a very unmagical greenish tinge around their eyes.

In the back of his mind, somewhere in the heat and the flames and the fire, he wondered if they were feeling well.

It was that thought that brought him back. It took effort to pull himself out of… whatever that was. To calm himself back down to normal levels. From the corner of his eyes, he could see a couple nurses, watching him with worried and wary eyes. They clenched buckets full of water, just in case. They didn’t know those buckets of water might as well kill him.

And, perhaps, that was a good thing.

Wrangling up the fire as though rolling yarn into a ball, Grillby returned to himself. He felt present. In control. And a bit ashamed of his outburst. Then, he realized that the skeleton had been trying to talk to him, standing in between the elemental and the human.

“Firefly—” Gaster sputtered, “they’re not hurting anyone, see?” His bony hands gestured to Cooper, the pile of dust behind them. “They were trying to help. And they feel—they feel for these monsters, Grillby! They’re a human but they have _empathy_ …”

“I saw,” he said.

“Remember,” the skeleton continued, “remember when we talked about you figuring it out in the moment?”

“I do,” he said. When Gaster gave him an expectant look, he glanced around to Cooper. Some of the fear had drained from their face. The pale green hue lingered, though. The trails of tears on their face highlighted how unnaturally bright their skin looked.

“And?” the skeleton asked, impatient.

Looking back to his friend, Grillby sighed, “I need bring them to King Asgore.”

Though unhappy, Gaster nodded his silent assent. He helped Cooper stand, their knees sore from sitting on them so long. Looking at their clothing, the dust scattered on their sleeves and torso, the skeleton frowned.

“Can… can I change, first?” The question, just over a whisper, came from Cooper. Grillby had almost forgotten what their voice sounded like, when it was scared. He nodded, standing on the other side of them as they marched back to the tent. Gaster handed them one of his extra shirts, one that laced up all the way, and a pair of trousers. He took their dusty clothes and shook them outside. A passing monster asked why he was doing laundry there. Tense, Gaster laughed and told them it was just some dirt. The elemental could tell it was a façade, but it seemed to work.

After a minute, Cooper walked out of the tent. They had strung up the shirt backwards. “So, I can show King Asgore what the runes look like,” they explained. Gaster nodded, throwing their cloak over their shoulders. The green paleness of their face seemed more unnatural in the cold sunlight. Compared to the skeleton beside them, they were whiter. Ashen, perhaps.

Though he tried to convince himself it was the best choice, Grillby still felt guilt. He wasn’t going to kill them. Maybe King Asgore would. But the blame would be shifted. Or would it? He mulled over these thoughts as he looked Cooper up and down, nodding to himself. “Ready?”

“As I’ll ever be.” It was a good attempt at bravery. But it didn’t succeed.

Grillby escorted them over to King Asgore’s permanent tent. Of the monsters at the fort, many of them knew about Cooper. Might’ve seen them in passing, or heard stories about them, or even been in their care in the infirmary tent. A few smiled to them as they passed. Others gawked, openly—slack-jawed and oblivious to how idiotic they looked. Two or three spat in their direction. Grillby tried not to spark in retaliation.

It was true that, to the untrained eye, they seemed as chipper as ever. Their copper head was held high, blazing a bright color in the sunlight. _Almost like fire_ , Grillby thought. It sprang from his mind without his consent, a stray thing he should quash. But, upon thought, he kind of liked it. A fire elemental, escorting the fire-haired human. It was quite the pair.

When they reached King Asgore’s tent, Terros announced them. The seconds between then and Cooper’s entrance seemed to stretch for much longer. Minutes or hours even. The tension in his stomach made him feel like he was going to pop and sizzle up, like a firework.

Cooper just waited. Patient, unmoving, and a bit green.

And then they went inside. When Grillby tried to enter, Terros put a stone hand on the fire elemental’s shoulder. With a simple shake of his head, Grillby stood rooted to the spot.

Seconds stretched into minutes. Minutes stretched into an hour. Daylight was fading, and as the sunlight passed overhead, Grillby paced. He started in small circles, just before the tent’s opening. Then his circles spiraled outwards, eventually circling the whole tent. His nervous energy made him flicker and pulse with wild, uncontrollable colors. From his sentinel position, Terros watched, neither amused nor upset. Perhaps, if he allowed himself, Grillby thought the stone elemental was curious.

Nobody’d brought a human mage to see Asgore before.

Eventually, it was time for Grillby to call up his company of soldiers and send them to dinner. Sighing, he trudged back towards camp as the horn sounded for the end of chores. Gaster, as energetic as ever, nervously signed at him. A shrug was all the answer the elemental could give.

His company mustered. Roll call came and went. He sent them off to the mess hall. Looking over his shoulder the whole time.

It’d been hours, now. No magic in the air, none that smelled like decaying leaves and new beginnings. The only loud voices in the camp were raucous laughter, friendly insults, and shouted commands. Not the sounds of a fight.

Eventually, as the sun set, as the moon rose, and as the stars twinkled into brightness, Cooper walked back. Their face was a bit greenish, but the paleness was gone. Instead, was a light of happiness. A worry lifted form their shoulders.

“You’re safe?” Gaster’s voice called over the dwindling coals.

“I’m safe,” they answered back.

In a heartbeat, they were enveloped by two monsters, hugging them as though their life depended on it. Because it did. But it wouldn’t anymore.

**Notes for the Chapter:**

> And with that, dear reader, the story is finished. Of course I had to leave it somewhat resolved and not fully resolved.
> 
> Depending on the next chapters in Casting Rain (by the way you should check it out here: https://archiveofourown.org/works/6119951 ) I may either add or change certain things that happen. 
> 
> Who knows, dear reader. I could just delete this thing wholesale in a moment of sheer embarrassment and panic! Though, at this point, I doubt it. If anything, AO3 has shown me that imperfection is, itself, a kind of perfection. Perfect, in the fact that it's at least done and out there for others to see.
> 
> If you're looking for more fic by me, I have another thing you can read! Are you craving Sans as a brother/dunkle? Do you think that maybe it would've been a good idea to have the monsters beat up on someone who isn't, say, eight and a half? Do you like having protagonists who are, in fact, yourself? Do you want to feel a writer squirm while she attempts to write in the most obnoxious form possible: second person present tense? Read my fic about a poor human with too much baggage here: https://archiveofourown.org/works/13999536
> 
> If you are looking for more fic in general, because you're tired of my writing style and want something new, I highly suggest looking at Casting Rain! (I mean, if you haven't already, we've got some talking to do, buddy.) It's here: https://archiveofourown.org/works/6119951
> 
> P.S. I'm not sure how linking works here, but you can always highlight and right click. It should give you an option to go to those pages. ~~~The more you know!!!~~~


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